So, I was wondering what you do for a living
or if you have ever been exposed to asbestos, smog, coal,
or other inorganic chemicals that could be the issue. Our lungs are an organ that regenerate and 2 years is enough time that you tissue should all be new by now. When I lived in Los Angeles I used to bike 40 miles a day, but ended up with a smokers cough and had phlegm with black in it and didn't smoke anything, so I know it was do to my environment.